I. Field of the Invention
The present invention relates to stucco walls. More specifically, the present invention relates to a novel and improved method of forming in a stucco wall a barrier to prevent the upward leaching of water-borne minerals and salts from the soil through the stucco wall.
II. Description of the Related Art
In many types of building structures stuccoing is one method of forming the exterior walls. Buildings which include stucco walls are typically residences and smaller commercial buildings. Stuccoing is preferred in many locations due to its inherent durability and ability to incorporate aesthetically appealing textures and colors.
In fabricating a building which will include an exterior stucco wall, a concrete foundation footing is formed about the perimeter of the building where the exterior walls are to be located. The footing typically extends downward below the soil level adjacent the building.
A wooden floor joist plate is then typically affixed to the top of the footing. Wooden studs are then horizontally positioned upon and affixed to the joist plate as is well known in conventional construction framing techniques. A lath layer is then formed over the studs. The lath layer is typically comprised of a layer of tar paper that is stapled or nailed to the studs. Overlying the tar paper, a metal wire mesh or screen is also stapled or nailed to the papered studs. The paper and wire mesh respectively provide a substantially water-tight backing and carrier for the stucco.
A base layer or "brown coat" of stucco is typically applied directly against the lath layer. The stucco base layer is typically applied by spraying the stucco material directly upon the lath layer. The stucco base layer is formed from a mixture typically comprised water mixed with four parts of sand and one part of cement. Various other materials or compositions may be added to the mixture to achieve various results. Water is added to the base layer mixture to provide a vehicle for application of the stucco. The base layer is typically applied to achieve a thickness of approximately three-quarters of an inch. Subsequent to the application of the stucco mixture to the lath layer, the water begins to dry out of the mixture resulting in the hardening of the stucco base layer.
An outer layer of stucco, also known as a "finish coat"or "color coat", is then applied to the base layer. The stucco outer layer is typically applied by spraying a mixture forming the stucco outer layer directly upon the stucco base layer. The stucco outer layer is formed from a mixture typically comprised water mixed with three parts of sand, one part of cement and one part of lime. Various other materials or compositions may also be added to the mixture to achieve various results. For example, pigments may be added to the mixture to give color to the finish. Water is again added to the outer layer mixture to provide a vehicle for application of the stucco. The outer layer is typically applied to achieve a thickness of approximately one-eighth of an inch. Subsequent to the application of the stucco mixture to the base layer, the water begins to dry out of the mixture resulting in the hardening of the stucco outer layer.
The addition of one part of lime, in combination with the reduction of one part of sand, to the mixture of the stucco outer layer, as compared to mixture of the stucco base layer, serves to increase the density of the stucco outer layer. The increase in density of the stucco outer layer gives it an enhanced resistance to the moisture. Correspondingly, the porosity and the ability of moisture to travel in the stucco base layer is greater than that of the stucco outer layer.
In the construction of older structures, especially homes, the lath layer extends downwardly along the footing below the soil level. The stucco base and outer layers are then applied to the lath layer, also extending below the soil level. As construction of the structure is completed the soil is pushed up against the stucco outer layer.
As time goes by, moisture from the soil is able to seep beneath the bottom of the stucco outer layer and into the stucco base layer. If the foundation footing is constructed with a foot portion, the moisture may seep between the foundation foot portion and the bottom of the stucco outer layer into the stucco base layer. This moisture that seeps into the stucco base layer contains mineral and salts that originated from the soil. The moisture travels upwardly generally only in the stucco base layer due to its lower porosity than that of the stucco outer layer. Soil moisture is known to travel in the stucco base layer upwardly from the soil level until an evaporation point is reached. The evaporation point is typically on an average of three feet, and on occasion up to five feet, from the soil level.
The minerals and salts that are carried by the moisture through the stucco base layer is damaging to both the stucco base and outer layers. Over time, the moisture leaches from the stucco base layer through to the stucco outer layer. The evaporation of the moisture leaves the minerals and salts remaining in the stucco layers. The remaining minerals and salts cause a deterioration of the stucco layers. These minerals and salts typically appear as an efflorescence upon the outer stucco layer.
In the construction of more modern homes, a device called an FHA screed is installed under the lath layer at the floor joist plate line. The screed is typically affixed to the floor joist plate by nails extending into the floor joist plate. The screed is intended to be used in applications where the soil level is below the floor joist plate line. The stucco layers are then applied to the lath layer which ends at a top portion of the screed. The lath layer and stucco layers, therefore, do not extend below the screed. The footing, which is typically not constructed to be aesthetically appealing, is therefore exposed in the region below the screed and above the soil level.
Several attempts have been made to use the screed in the re-stuccoing of older homes which have the stucco layers extending below the soil level. The use of the screed is to prevent damage to the stucco layers as a result of the upward leaching of soil minerals and salts as previously discussed. The attempts in using the screed in the restuccoing of this type of older homes has been unsuccessful for several reasons.
One reason that the screed is undesirable in the restuccoing of older homes is that the waterproof integrity of the lath layer is compromised. To affix the screed to the floor joist plate, the lath layer must be removed in the region about the floor joist plate. Removal of the lath layer can result in a potential path for moisture to leak into the framing structure.
In other re-stuccoing applications, the screed is not a preferred mechanism to prevent stucco damage from soil originated moisture. The screed is intended to be used where no stucco extend below the screed. In certain homes, such as historical landmarks or homes that the owners desire to retain the original appearance, the use of the screed would permit the footing to be exposed below the floor joist plate line. In these situations, the use of the screed where the structure has a high floor joist plate line relative to the soil line would greatly detract from the appearance of the structure.
In other re-stuccoing applications the screed cannot be used. These cases arise where the floor joist plate line is below soil level. The screed is intended to be affixed to the wall at the floor joist plate line. The use of the screed affixed to a wall having a floor joist plate line below soil level does not prevent soil moisture from penetrating the stucco base layer between the screed and the stucco outer layer. In addition, soil moisture may seep into the wall framing by violation of the integrity of the lath layer by the insertion of the screed under the lath layer.
It is, therefore, an object of the present invention to provide a novel and improved method for retarding damage to stucco walls from water-borne minerals and salts emanating from the soil.
It is another object of the present invention to provide a method for forming in a stucco wall a barrier to moisture leaching in the stucco layers.
It is yet another object of the present invention to provide a method for constructing a soil moisture barrier in the stucco so as to retain the original external appearance of the wall.
It is still a further object of the present invention to provide an improved soil moisture barrier for a stucco wall.